I used one of these for two years and thought it was great:
[ame="http://www.amazon.com/La-Crosse-Technology-WS-8418U-IT-Digital/dp/B0016MYATS/ref=sr_1_8?ie=UTF8&qid=1356966616&sr=8-8&keywords=lacross+clock"]Amazon.com: La Crosse Technology WS-8418U-IT Atomic Digital Wall Clock with Moon Phase: Home & Kitchen[/ame]
My big complaints: It's overkill. You don't need cycle of the moon or "outdoors temp" for a comp clock. Also, while you can make it display seconds instead of the outdoors temp, it's a few button presses every time you install batteries. I sold it to another competitor because....
I still had this clock on my Amazon wishlist and some one bought it for me:
[ame="http://www.amazon.com/La-Crosse-Technology-WT-8005U-S-Temperature/dp/B002BDV8DC/ref=sr_1_7?ie=UTF8&qid=1356966797&sr=8-7&keywords=lacross+clock"]Amazon.com: La Crosse Technology WT-8005U-S Atomic Digital Wall Clock with Indoor Temperature, Silver: Home & Kitchen[/ame]
It's more affordable, isn't as much overkill, and has seconds by the clock. I haven't used it yet, but I can't imagine it being any worse.
There is a third clock available, that I don't think was around before. It has two temps like the first clock, but no moon, and is the same size as the second one. It only costs $1 more on Amazon, but do you need the display to be crowded? Still, I like these clocks. I recommend either storing the clock somewhere where it can get a signal, or taking out the batteries between comps because not getting a signal will drain the battery.
dmp
EDIT: Maybe you do want outdoor temp if you use an RV or trailer. It would be nice to know the temp when you get up first thing in the morning. I've always competed in an EZ-UP, so the "indoor temp" was the "outdoor temp."